Package: guix-patches;
Reported by: Sarah Morgensen <iskarian <at> mgsn.dev>
Date: Sat, 19 Jun 2021 00:53:02 UTC
Severity: normal
Tags: patch
Done: Ludovic Courtès <ludo <at> gnu.org>
Bug is archived. No further changes may be made.
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From: help-debbugs <at> gnu.org (GNU bug Tracking System) To: Sarah Morgensen <iskarian <at> mgsn.dev> Subject: bug#49107: closed (Re: bug#49107: [PATCH core-updates] gnu: fontconfig: Use (locally) deterministic caching) Date: Mon, 12 Jul 2021 08:32:02 +0000
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Your bug report #49107: [PATCH core-updates] gnu: fontconfig: Use (locally) deterministic caching which was filed against the guix-patches package, has been closed. The explanation is attached below, along with your original report. If you require more details, please reply to 49107 <at> debbugs.gnu.org. -- 49107: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=49107 GNU Bug Tracking System Contact help-debbugs <at> gnu.org with problems
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From: Ludovic Courtès <ludo <at> gnu.org> To: Sarah Morgensen <iskarian <at> mgsn.dev> Cc: 49107-done <at> debbugs.gnu.org Subject: Re: bug#49107: [PATCH core-updates] gnu: fontconfig: Use (locally) deterministic caching Date: Mon, 12 Jul 2021 10:30:56 +0200Hi, Sarah Morgensen <iskarian <at> mgsn.dev> skribis: > Ludovic Courtès <ludo <at> gnu.org> writes: [...] >> Does Fontconfig stats all these files every time an application starts? >> Did you compare ‘strace -c some app’ with and without this change, to >> get an idea of what it costs? > > I *believe* it does so whenever an application calls FcFontList or such, > which is usually on startup. I haven't done tracing with an application > that actually uses FcFontList, but I just now ran a naive test, along > the lines of: > > $ fc-cache -rf > $ strace -c fc-list > > The old fc-list: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 28.50 0.000226 0 228 142 openat > 22.19 0.000176 1 136 26 access > 11.10 0.000088 0 133 70 stat > 5.93 0.000047 0 86 close > 5.55 0.000044 2 22 fstatfs > 5.30 0.000042 0 54 37 readlink > 4.54 0.000036 4 8 munmap > 3.78 0.000030 0 70 mmap > 2.65 0.000021 1 20 write > 2.52 0.000020 0 104 read > 2.52 0.000020 0 40 fstat > 1.89 0.000015 1 8 fadvise64 > 1.77 0.000014 1 10 getpid > 0.88 0.000007 0 10 brk > 0.63 0.000005 0 35 getrandom > 0.25 0.000002 2 1 1 ioctl > 0.00 0.000000 0 15 mprotect > 0.00 0.000000 0 2 rt_sigaction > 0.00 0.000000 0 1 rt_sigprocmask > 0.00 0.000000 0 1 execve > 0.00 0.000000 0 1 arch_prctl > 0.00 0.000000 0 1 futex > 0.00 0.000000 0 4 getdents64 > 0.00 0.000000 0 1 set_tid_address > 0.00 0.000000 0 1 set_robust_list > 0.00 0.000000 0 1 prlimit64 > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.000793 0 993 276 total > > > And the patched fc-list: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 17.19 0.000125 0 126 11 access > 14.44 0.000105 0 126 52 openat > 12.24 0.000089 1 55 mmap > 10.32 0.000075 0 99 read > 8.67 0.000063 4 15 mprotect > 8.25 0.000060 0 94 6 newfstatat > 5.50 0.000040 0 74 close > 5.23 0.000038 0 58 40 readlink > 4.68 0.000034 34 1 set_tid_address > 3.30 0.000024 0 38 getrandom > 3.16 0.000023 1 13 pread64 > 1.65 0.000012 0 26 getdents64 > 1.51 0.000011 1 9 brk > 1.10 0.000008 4 2 rt_sigaction > 0.83 0.000006 0 9 munmap > 0.55 0.000004 4 1 rt_sigprocmask > 0.55 0.000004 4 1 prlimit64 > 0.41 0.000003 3 1 arch_prctl > 0.41 0.000003 3 1 set_robust_list > 0.00 0.000000 0 20 write > 0.00 0.000000 0 1 1 ioctl > 0.00 0.000000 0 1 execve > 0.00 0.000000 0 1 sysinfo > 0.00 0.000000 0 11 fstatfs > 0.00 0.000000 0 8 fadvise64 > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.000727 0 791 110 total > > Now that is unexpected! There are actually less stats and opens. I'm > stumped! My profile has about 20 font packages (about 450 actual files) > installed. For reference, for both versions, `fc-cache -rf` yields about > 3700 stats; and `fc-cache` yeilds about 300... Well, even better. :-) I went ahead and applied the patch. ‘fontconfig-minimal’ builds fine; ‘fonconfig’ (with documentation) fails to build its PDF documentation, but that’s not related to this change. > I still wish we could address it "properly" by generating a cache at > profile generation time... but it looks like fontconfig embeds the full > paths of fonts in the cache (including username, since fonts are under > ~/.guix-profile), so I doubt such a cache would work. I plan to try it > eventually anyway (or perhaps someone else will), but in the meantime, > this looks like the 80% solution. Yeah. It could be that each font package could contain its own cache, and the profile hook would just assemble all these caches (provided the file format makes it possible without too much of a headache). Thanks! Ludo’.
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From: Sarah Morgensen <iskarian <at> mgsn.dev> To: guix-patches <at> gnu.org Subject: [PATCH core-updates] gnu: fontconfig: Use (locally) deterministic caching Date: Fri, 18 Jun 2021 17:52:05 -0700Make fontconfig use directory contents rather than modification time to determine cache validity (by pretending that mtime is broken). * gnu/packages/patches/fontconfig-cache-ignore-mtime.patch: New file. * gnu/local.mk (dist_patch_DATA): Register it. * gnu/packages/fontutils.scm (fontconfig)[source]: Use it. [arguments]: Unset SOURCE_DATE_EPOCH for tests. --- gnu/local.mk | 1 + gnu/packages/fontutils.scm | 7 ++++++- .../patches/fontconfig-cache-ignore-mtime.patch | 15 +++++++++++++++ 3 files changed, 22 insertions(+), 1 deletion(-) create mode 100644 gnu/packages/patches/fontconfig-cache-ignore-mtime.patch Hello Guix, This patch attempts to make fontconfig's caching work seamlessly on Guix, instead of requiring users to manually run `fc-cache -f` after installing or removing fonts. This addresses <https://issues.guix.gnu.org/18640>. Fontconfig usually uses a directory's mtime as its checksum. However, when fontconfig detects a "broken mtime" filesystem, it will generate a directory checksum from the directory listing contents. This is slightly slower, as it has to stat all the files in all font directories. Unconditionally enabling this mode should get us more regular behavior. I am not confident this method is fully deterministic; particular filesystem capabilities may still be an implicit imput in the checksums. This should only matter when distributing pre-generated caches. Fontconfig does honor SOURCE_DATE_EPOCH, but without a reliable mtime, fontconfig has no way of knowing when to update such a cache. SOURCE_DATE_EPOCH is now disabled for the tests because they assume working cache invalidation. I have tested this patch on x86-64. diff --git a/gnu/local.mk b/gnu/local.mk index c57e587e84..1d26c9e7c7 100644 --- a/gnu/local.mk +++ b/gnu/local.mk @@ -1012,6 +1012,7 @@ dist_patch_DATA = \ %D%/packages/patches/fifo-map-remove-catch.hpp.patch \ %D%/packages/patches/findutils-localstatedir.patch \ %D%/packages/patches/flann-cmake-3.11.patch \ + %D%/packages/patches/fontconfig-cache-ignore-mtime.patch \ %D%/packages/patches/foobillard++-pkg-config.patch \ %D%/packages/patches/foomatic-filters-CVE-2015-8327.patch \ %D%/packages/patches/foomatic-filters-CVE-2015-8560.patch \ diff --git a/gnu/packages/fontutils.scm b/gnu/packages/fontutils.scm index dbce5beba8..0ee51a792e 100644 --- a/gnu/packages/fontutils.scm +++ b/gnu/packages/fontutils.scm @@ -14,6 +14,7 @@ ;;; Copyright © 2020 Nicolas Goaziou <mail <at> nicolasgoaziou.fr> ;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer <at> gmail.com> ;;; Copyright © 2020, 2021 Nicolas Goaziou <mail <at> nicolasgoaziou.fr> +;;; Copyright © 2021 Sarah Morgensen <iskarian <at> mgsn.dev> ;;; ;;; This file is part of GNU Guix. ;;; @@ -331,7 +332,8 @@ Font Format (WOFF).") "https://www.freedesktop.org/software/" "fontconfig/release/fontconfig-" version ".tar.xz")) (sha256 (base32 - "1850q4k80yxma5g3yxkvyv8i5a3xqzswwml8gjy3jmywx8qqd5pa")))) + "1850q4k80yxma5g3yxkvyv8i5a3xqzswwml8gjy3jmywx8qqd5pa")) + (patches (search-patches "fontconfig-cache-ignore-mtime.patch")))) (build-system gnu-build-system) ;; In Requires or Requires.private of fontconfig.pc. (propagated-inputs `(("expat" ,expat) @@ -362,6 +364,9 @@ Font Format (WOFF).") (modify-phases %standard-phases (add-before 'check 'skip-problematic-tests (lambda _ + ;; SOURCE_DATE_EPOCH doesn't make sense when ignoring mtime + (unsetenv "SOURCE_DATE_EPOCH") + (substitute* "test/run-test.sh" ;; The crbug1004254 test attempts to fetch fonts from the ;; network. diff --git a/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch b/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch new file mode 100644 index 0000000000..b6e942ee10 --- /dev/null +++ b/gnu/packages/patches/fontconfig-cache-ignore-mtime.patch @@ -0,0 +1,15 @@ +Pretend that stat's mtime is broken, so that the fontconfig cache does not +depend upon modification time to determine if a cache is stale. + +diff --git a/src/fcstat.c b/src/fcstat.c +index 5a2bd7c..d603a96 100644 +--- a/src/fcstat.c ++++ b/src/fcstat.c +@@ -431,6 +431,7 @@ FcIsFsMmapSafe (int fd) + FcBool + FcIsFsMtimeBroken (const FcChar8 *dir) + { ++ return FcTrue; + int fd = FcOpen ((const char *) dir, O_RDONLY); + + if (fd != -1) base-commit: bcdc13454c4afab37b650d4bbfa95e539060619f -- 2.31.1
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